In many agricultural applications, particulate materials such as seed, fertilizer, herbicide and insecticide are applied to the ground or other surface being worked. It is often necessary to precisely control and meter the application of the agricultural particulate materials to the surface. As a result, conventional material applicating systems generally include a hopper, bin or other structure which provides a compartment for containing or storing the material and a metering device which receives material from the compartment and which meters and delivers the material at a precisely controlled rate to the surface being worked.
In many fields, the surface being worked varies from location to location. For example, a single path across a field may traverse different terrains, different moisture levels, different nutritional levels, different insect populations and different weed populations. As a result, to optimize crop yield and to most efficiently and effectively use the applied agricultural particulate material, it is often necessary to vary not only the rate at which the agricultural particulate material is applied to the surface but also the specific type or variety of agricultural particulate material being applied to the surface. For example, when traveling through a wet spot in a field, it may be advantageous to switch from a first variety of seed to a second variety of seed which is more suited to the high moisture level. Unfortunately, switching between types of agricultural particulate material is extremely difficult and time consuming. Switching between different types of agricultural particulate material usually requires the operator to empty the existing material from the compartment and then manually refill the compartment with the other type of agricultural particulate material. Alternatively, other material delivery systems include multiple compartments, wherein each compartment has its own metering device or mechanism which delivers agricultural particulate material into a central delivery tube. Although such systems are capable of delivering different agricultural particulate materials to the surface being worked, such systems require individual metering devices for each compartment and for each type of material. As a result, such systems are space consuming and expensive.
Thus, there is a continuing need for a material delivery system which is capable of selectively metering and delivering different types of agricultural particulate material to the surface being worked using a single meter. There is also a continuing need for a system which can reliably and predictably switch between the application of different types of agricultural particulate material "on-the-go" without substantial mixing of different materials as the delivery system is transported across the field.